Electron discharge device and associated cavity resonator circuit



Sept, w, E950 L. s. NERGAARD 2,522,836

ELECTRON DISCHARGE DEVICE AND ASSOCIATED cAvITY RESONATOR CIRCUIT Filed Oct. 21, 1944 INVENTORl A w .5A/MMM ORNE Patented Sept. 19, 1950 ELECTRON DISCHARGE DEVICE AND ASSO- lCIATED CAVITY RESONATOR `CIRCUIT Leon S. Nergaard, Princeton, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application October 21, 1944, Serial No. 559,700

10 Claims. l

My invention relates to electron discharge devices and associated circuits, more particularly to such devices and circuits useful at very high frequencies.

An object of my invention is to provide an electron discharge device and associated circuit particularly suitable for high frequency operation and capable of delivering large amounts of power.

Another object of my invention is to provide an electron discharge device which can deliver large amounts of power at high frequencies, but which is nevertheless small and compact, has few parts, and lends itself readily to manufacture.

A further object of my invention is to provide such a device having a low internal reactance which permits the use of a larger external circuit, that is a device which will function at higher frequencies with an external circuit and thus permit tuning over a considerable range.

A more specific object of my invention is to provide an electron discharge device in which the electrodes although closely spaced are firmly and rigidly supported with respect to each other.

Another specific object of my invention is to provide an electron discharge device in which the anode forms part of the tube envelope and in which the anode-to-envelope seal is protected against electron bombardment.

A further object of my invention is to provide an electron discharge device having electrode leads and supports which will merge into high frequency circuits of the cavity resonator type so that the internal reactances may be coupled smoothly to the external reactances which complete the circuit and thus reduce radio frequency losses and spurious modes of oscillation to a minimum.

A further object of my invention is to provide a cathode lead which facilitates incorporation of an electron discharge device into a cavity resonator circuit of the coaxial line type, and in which the heater circuit is shielded from the radio frequency field within the resonator.

Another object of my inevntion is to provide a lead and support for the cathode of an electron discharge device of the type described which lowers the radio frequency losses and reduces the number of parts required.

A further object of my invention is to provide an electron discharge device and associated circuit having improved coupling means for providing feedback when the device is employed as an oscillator.

A still further object of my invention is to provide a cavity resonator circuit in which the circuit has large dimensions but permits operation at high frequencies.

A still more specific object of my invention is to provide an electron discharge device and associated cavity resonator circuit in which the cavity resonator circuit is designed to permit assembly of a plurality of such devices into a parallel arrangement having a single output.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawing in which Figure 1 is a longitudnal section of an electron discharge device and associated cavity resonator circuit made according to my invention, and Figure 2 is a perspective showing a plurality of devices and cavity resonators assembled as a single unit for parallel operation.

According to my invention I provide an electron discharge device having an indirectly heated cathode I0 within which is mounted the heater I I. The cathode is surrounded by a cup-shaped grid I2, and both nested within the anode I3 which is elongated in shape and tapers or increases in a transverse section from the inner open end of the anode to the outside of the anode, the outer end of the anode being provided with heat radiating iins I4. The grid is mounted on a transverse flange-like s uppgrt and lead I5 between which and a collar I6 supprtdat'th' outer end of the anode is sealed a flared collar I 'I of insulating material, preferably glass, for providing with the anode I3 an envelope. As shown in Figure 1, collar Il has substantially the same taper as the adjacent surface of the anode and said collar is positioned relatively close to the anode in order to reduce internal rectance to a minimum. The Hangt-line support which provides a ring seal also serv''s"`s"t "wgidcontact to the cavity resonator'ircuits'.

The cathode'issuppr'ted'byaplurality of leads I9 from a collar I8, an inner conductoi` Il and collar I8 serving as leads for the cathode heater. 'I'he envelope is completed by means of the cupshaped insulating members I9 sealed between the grid ring I5 and the cathode collar I8 and the disc member I8 of insulating material, preferably glass, sealed between the conductor 20 and the cathode collar IB.

In assembly the cathode and grid are first mounted as a unit and the anode provided with the flange I3' diffusion sealed to the ange I6' carrying the collar I6. The anode is so designed that heat is eiciently conducted through the exterior to which the radiating fins I4 are attached. Inasmuch as the total heat to be conducted away from the anode surface is greater at the closed end of the anode, the area is made larger to facilitate this transfer of heat. The envelope is so designed that the distance between the seal is great while at the same time the seals, particularly the anode seal, are well protected from stray electron bombardment by the shape of the anode.

In accordance with my invention I provide a novel cavity resonator circuit arrangement which facilitates grouping of a plurality of devices around a common output resonator and also a novel means for controlling the feedback on the device to be used as an oscillator.

A coaxial line type resonator is coupled between the cathode and the grid and comprises an outer tubular member 2| and an inner tubular member 22 closed by a conducting disc member 23. The inner tubular member 22 is provided with spring fingers 24 contacting the cathode collar, and spring ngers 25 on the outside member 2| contact the grid-ring;0 These fingers are insulatingly supported fro the outer tubular member 2| by means of the insulating collar 26, preferably of mica, and are capacity coupled to outer tubular member to permit the flow of radio frequency currents between the grid and the cathode through thefresmator. A lead 21 may be connected through the spring lingers 25 connected to the grid for permitting biasing to be applied.` A tube 28 may fbe utilized to direct cooling auiwiuthwrnthegespnator. Tuning may rnplished by the usual tuning condenser element 29 adjusted by means of the insulating handle 3B. The inner cathode lead 20 is connected to clamp 3| having a lead 32 for providing a cathode heater circuit.

The output resonator comprises an outer tubular member and the inner tubular member 2| closed by the flat conducting collar 36. Spring fingers 35 are insulatingly supported from the outer conducting member 35 by means of insulating collar 31, preferably of mica. As in the case of the grid circuit the ngers are capacity coupled to the outer tubular member for radio frequency currents. Energy is taken out of the resonator by means of coaxial line comprising conductors 38 and 39.

To provide a control for the feedback, inner tubular member 2| is provided with a pair of parallel longitudinal extending slots 40 leaving conductor 4| therebetween, which conductor carries current and creates a magnetic field which couples the inner and outer resonators. The degree of coupling is determined by slide 42 operated by insulating rod 43 which varies the effective length of the conductor 4| and hence the amount of magnetic coupling. The slots may be looked upon as a single aperture with a conductor extending across the aperture.

In Figure 2 I show a plurality of devices such as shown in Figure 1 coupled to a common output resonator comprising outer and inner conductors 45 and 46 from which energy may be coupled by means of coaxial line 41.

The advantages of this arrangement are that it increases the power output of the transmitter. If a tube fails or a unit circuit fails, the unit can be removed for repair or replacement of the tube without shutting down the entire transmitter for a protracted period which is necessary with the usual ring circuits. It is possible to have several spare unit oscillators which can be plugged in in place of any unit which has failed. This involves time of a minute or less. The transmitter can then be operated at full power output at all times except for such short periods as are necessary for replacing units in the event of a failure.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is:

l. An electron discharge device having a cathode, grid and anode, a cavity resonator coupled between said grid and cathode and a second cavity resonator coupled between said grid and anode, said resonators having a common wall, said wall having an aperture therein and a conductor extending across said aperture, and means slidaibly supported over said aperture for movement along said conductor for varying the size of said aperture and the effective length of said conductor to vary the coupling between said resonators.

2. An electron discharge device having a cathode, a grid and an anode, a coaxial line cavity resonator coupled between said cathode and grid, a second coaxial line resonator coupled between said grid and anode, said resonators having a common wall, said common wall having a plurality of adjacent parallel slots therein for coupling said resonators, and means in contact with said wall and movable along said slots for vary- I ing the coupling effect due to said slots.

3. An electron discharge device having a cathode, a grid and an anode, a coaxial line cavity resonator including a pair of coaxial tubular conductors coupled between said cathode and grid, a second coaxial line resonator coupled between said grid and anode and including a third coaxial tubular conductor surrounding said pair of conductors, said resonators having a common wall, said common wall having a plurality of adjacent parallel slots therein for coupling said resonators together, and a slide in contact with said wall and movable along said slots for varying the coupling effect due to said slots.

4. An electron discharge device having a cathode, grid and an anode, said grid being provided with a transverse ring support, a cavity resonator connected between said cathode and said ring support and comprising a conductor and a first tubular member surrounding said conductor, and a second tubular member surrounding said conductor and first tubular member and providing with the tubular member a cavity resonator coupled between said anode and said grid ring, said first tubular member having a pair of parallel slots therein for coupling said resonators, and means including a conducting element straddling said slots and movable longitudinally thereovcr to control the coupling between said resonators.

5. An electron discharge device having a cathode, grid and anode, a conducting member coupled to said cathode, a first tubular member surrounding said conducting member and coupled to said grid, and a second tubular member surrounding said conducting member and said first tubular member and coupled to said anode, one end of each of said tubular members lying in a common plane and connected together, said conducting member and said tubular members being successively longer, said second tubular member extending substantially the length of said electron discharge device and substantially enclosing said electron discharge device and said conducting member and said first tubular member.

6. An electron discharge device having a. cuplike cathode, a grid and anode in nested relationship, a rst tubular member coupled to said cathode, a second tubular member surrounding said rst tubular member and coupled to said grid, and a third tubular member surrounding said rst and second tubular members and coupled to said anode, one end of each of said tubular members lying in a common plane and electrically connected together, said tubular members being successively longer from the rst to the third tubular members, said third tubular member extending substantially the length of said electron discharge device and substantially enclosing said electron discharge device and other members.

7. An electron discharge device having a cath- 0de, grid and a cup-shaped anode in nested relationship, said anode increasing in transverse section from the open end of said anode toward the other end of said anode, said grid being provided with a transverse ring-shaped lead and support, an outwardly iiared insulating collar member having substantially the same taper as the anode and sealed between said grid lead and support and the end of said anode remote from said grid lead and support, and an insulating end member sealed between said cathode and said grid lead and support.

8. An electron discharge device having a cathode. a cup-shaped grid and a cup-shaped anode in nested relationship, said anode increasing in transverse section from the open end of said anode toward the other` end of said anode, said grid being provided with a transverse ring-shaped lead and support, an outwardly flared insulating collar member having substantially the same taper as the anode sealed between said grid lead and support and the end of said anode remote from said grid ring and positioned relatively close to said anode, said cathode being provided with a collar-like lead and support, and an insulating end member sealed between said collar-like lead and support and said grid lead and support.

9. An electron discharge device having a cupshaped cathode, a cup-shaped grid and a cupshaped anode in nested relationship, the transverse section of said anode increasing from the open end of said anode toward the closed end of said anode, the internal diameter of the anode being substantially uniform, a collar coaxial with said cathode and grid and secured to the outer end of said anode, a, ring lead and support for said grid, and an insulating collar having substantially the same taper as the anode and sealed between said ring lead and support and said collar, the diameter of said ring lead and support being less than the diameter of said collar, and an insulating cup-shaped closure member sealed between said cathode and the ring lead and support.

10. An electron discharge device having cupshaped cathode, grid and anode electrodes in nested relationship, the transverse section of said anode electrode increasing from the open end toward the closed end of said anode electrode, a transverse flange at the closed end of said anode electrode, a collar coaxial with said electrodes and secured to said ange and extending toward the open end of said anode electrode, a ring lead and support for said grid electrode, and a flared insulating collar having substantially the saine taper as the anode and sealed between the ring lead and said collar, the diameter of said ring lead and support being less than the diameter of said collar, and an insulating closure member sealed between said cathode electrode and the ring lead and support, and heat radiating fins mounted in the exterior of the closed end of said anode electrode.

LEON S. NERGAARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,153,728 `Southworth Apr. 11, 1939 2,228,939 Zottu et al. Jan. 14, 1941 2,267,128 Mouromtsei et al. Dec. 23, 1941 2,284,405 McArthur May 26, 1942 2,287,845 Varian et al June 30, 1942 2,314,794 Linder Mar. 23, 1943 2,333,295 Chevigny Nov. 2, 1943 2,419,578 Litton Apr. 29, 1947 2,423,819 Chevigny July 8, 1947 

